الفهرس 
Hippocampus:Only 14 pages are availabe for public view
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Abstract
The hippocampus, a medial, temporal lobe structure, is a part of the cerebral cortex and the limbic system. It comprises the hippocampus proper and the dentate gyrus, each is a three-layered cortex. The most important function of the hippocampus is consolidation of recent memories (especially episodic memories relating to personal events and related emotions) and spatial navigation. Aging is associated with specific impairments of learning and memory, some of which are similar to those caused by hippocampal damage. Studies of the effects of aging on hippocampal anatomy, physiology, plasticity, and network dynamics may lead to a better understanding of age-related cognitive deficits.
In the present work, twenty male Albino rats were utilized. They were obtained from the animal house of the Medical Research Center (MRC) of the Faculty of Medicine, Ain Shams University, and they were treated according to the guidelines of Ain shams Committee on Animal Research Ethics (CARE). The rats were divided into two groups; group A included ten male adult albino rats weighing from 100-150g and aged about six months, and group B included ten male senile albino rats weighing from 250-300g and aged about two years. The hippocampi were obtained through parasagittal incision in one hemisphere and coronal incision in the other. Microscopic sections were prepared, sectioned, mounted on slides and stained by haematoxylin and eosin and silver stain (method of Glees). TUNEL immunohistochemistry and statistical analysis were done.
The current study revealed signs of degeneration in the senile rats hippocampi in the form of: significant decrease in the thickness of the principle cell layers, significant decrease in the count of principal nerve cells, decrease in the nerve fibers density, and significant increase in the apoptotic immunoreactivity in most of regions of senile rats hippocampus. Interestingly, CA2 region of senile rats’ hippocampi showed significant increase in the pyramidal cell layer thickness and pyramidal cells count which may reflect the importance of this region.
In conclusion, aging is associated with structural changes in the hippocampus that may lead to memory and learning impairment.